The second influential group of theories mentioned in the last chapter comprises the stimulus-response psychologies. Pavlov's classical conditioning experiment is well known: how by repeatedly sounding a bell before presenting food he induced a dog to salivate to the bell alone. The sound of the bell, an arbitrary neutral stimulus, became conditioned, producing automatically the same response as was reflexly produced by the unconditioned stimulus, the smell and sight of food. (This is the `official' terminology. In popular parlance, of course, it is the animal rather than the stimulus that becomes conditioned.) According to the theory, a new connection was established in the cerebral cortex of the animal by the repetition and association of the experimental procedure.

Running through the subsequent development of the theory is a trend which originated with Thorndike, an American contemporary of Pavlov, and has greatly influenced B. F. Skinner who regards Pavlovian conditioning as of much less importance in human learning than what he now calls operant (formerly operant conditioning). In contrast with the stimulus substitution of Pavlov, whereby a new conditioned stimulus produces the same response as the unconditioned stimulus, Thorndike's system amounted to a response substitution. A new (usually desired) response is made to the same stimulus: the `right' speech, note, typewriter key, is substituted for the `wrong' response previously made . to the `cue'. It is essentially a system of trial and error, success and failure, reward and punishment. This is the basis, it is fair to say, of Skinner's operant - his technical terms - positive and negative reinforcers, being the equivalent of reward and punishment in the vernacular.

As long ago as 1959, Noam Chomsky published a very long review of Skinner's book Verbal Behavior and showed that there was a kind of sleight of hand in Skinner's extrapolation of his carefully controlled experiments with rats in captivity to uncontrolled, everyday, human situations. His most telling point was that, out of the mass of external and internal stimulation to which the individual was subjected and the totality of his behaviour, Skinner picked out single elements and called them the stimulus and the response and assumed them to be connected, only because this connection fitted both the laboratory results and the theory. Devastating as this criticism was, Skinner went on his way as though nothing had ever been said, indeed he recently revealed to David Cohen that he did not read Chomsky's paper until ten years later.

Popper's refutation of conditioning centres on the idea of repetition. It follows from his rejection of Hume's psychological theory (page 14) that we - humans and animals in general - observe repetitions and then act in the expectation that these repetitions will go on recurring. But, says Popper: `All repetitions that we experience are approximate repetitions ... Repetition B of an event A is not identical with A or indistinguishable from A, but only more or less similar to A' (L.Sc.D. 520). Things which are similar but not identical are similar only in certain respects; and whether or not we regard things as being similar depends on whether we are interested in those respects. Popper illustrates his argument with diagrams which show that things may be similar in different respects and that similarity in one respect may easily be accompanied by dissimilarity in another (in The Logic of Scientific Discovery, Karl R. Popper, Hutchinson, Revised Edition 1968, Appendix * x, page 421).

A good example is the spuriously objective pick-theodd- one-out kind of question in which examinees are systematically put in the wrong. Seeing the similarity between the non-odd items presumes a point of view. The question is really `guess what I am thinking of' and is a good illustration of the need for criticism of experts in general. It is quite inconceivable that the examiner will have considered all the possibilities of similarity and dissimilarity in the words listed; and it is easily conceivable that the examinee will hit on one that was not considered when the question was set.

Popper goes on: `We must therefore replace, for the purposes of a psychological theory of the origins of our beliefs, the naive idea of events which are similar by the idea of events to which we react by interpreting them as similar' (C. R.45). For all of us seeing things as similar depends upon interpretation, anticipation, and expectation. We cannot therefore explain anticipation and expectation as being consequences of repetition. For even the first repetition-for-us would only be interpreted as such if it is seen as similar, and seeing something as similar depends upon expectation. Thus Popper was led, he said, by purely logical considerations to replace Hume's widely assumed, weaker, psychological theory of induction with the following:

"Without waiting passively for repetitions to impress or impose regularities on us, we actively try to impose regularities on the world. We try to discover similarities in it, and interpret it in terms invented by us. Without waiting for premises we jump to conclusions. (C.R.46)"

Pavlov's dog invents the theory that food follows the bell. All organisms are all the time inventing such theories, mainly unconsciously but actively. The theories are not passively instilled into them by the `conditioning' process. It is essentially a trial and error process, of conjectures open to subsequent refutation. The theories formed in this way may have to be discarded later.

Skinner's operant behaviour can, as I have mentioned, also be regarded as a trial and error process and may therefore seem to come to the same thing as what Popper describes. The vital difference is that Skinner does not allow that the spontaneous action, the trial, can be theory-directed, intelligently exploratory. He rules out of court the intervention of thoughts, ideas, theories, intentions. He does not deny that they exist; but regards them as mere `flotsam' accompanying the action. For him the trial in trial-and-error is not based on conjecture. It is blind and random; and words are nothing but the movement of the vocal cords.

This is another of those conceptual illusions that I mentioned in the first chapter (page 17): conspiracy, induction, instruction, and now, it looks as though the world imposes its pattern on the passive organism, but really the active organism tries out its guesses on the world and the world accepts or rejects them. In the physical world perhaps the best example of the same sort of thing is suction. There is no such thing as suction, conceived as a magnet-like force. When you `suck' up lemonade through a straw what really happens of course is that the atmospheric pressure forces some of the liquid up the straw into the region of lowered, but positive, pressure in your mouth. What looks like pull is really push. However the idea of suction remains convenient fiction as long as it is not taken too far - more than about thirty-four feet for water. The most powerful pump imaginable will not `suck' water from a greater depth than that. It is important to mention this fact that a false theory can be useful within some range, but manifestly and dangerously false outside that range. I can best illustrate this by adapting an example used by Popper in a slightly different context. Suppose the time is really five minutes past eleven. Then the statement `It is eleven o'clock' is untrue but more useful for most purposes than the true statement `It is between ten o'clock and midday'. However the generally useful eleven o'clock statement is a dangerous one for the purpose of catching a train timed to depart at 11.04. Newtonian physics, which is grossly inaccurate when velocities of the same order as that of light are concerned, is more useful than Einsteinian physics in the ordinary `practical' range.

But to return to the case in point, Popper's rejection of conditioning is of a piece with a central element in his philosophy, that there is no such thing as direct experience. The central mistake, he says, in the so-called commonsense theory of knowledge is the quest for certainty, which leads to `the singling out ... of sense data or sense impressions or immediate experiences as a secure basis of all knowledge. But ... these data or elements do not exist at all. They are the inventions', he adds, 'of hopeful philosophers, who have managed to bequeath them to the psychologists' (O.K.63).

He reaches his conclusion by logical means but the view that what seems to be directly experienced is really the result of interpretation of coded information is of course a fact of anatomy and physiology. At birth our brains are in the position of an underground military intelligence unit connected with the outside world only by telephone lines, most of which are unlabelled. Only by a lengthy process of cross reference can the brain attach labels so it can tell, at once and reliably, whence any particular message originates. Recent research on the eye has underlined the degree to which the brain interprets rather than merely receives data. The eye is, in optical terms, a very poor sort of camera, producing an extremely fuzzy image, much less clear than what we `see'. The brain compares the series of blurred images as the eye scans and deduces the clear image we `see' and even after years of experience we can still be deceived by `optical illusions'. The Necker cube, illustrated here, demonstrates two facts that are central to the theme of this book. The first is the one mentioned above that there is no such thing as direct experience. There are no sensory data corresponding to the bits of information that are stored in a computer. All perceptions are interpretations of coded signals, analogous to the reading of a non-standardized Morse code. The second fact is that the will or conscious intention can sometimes override unconscious reaction. The figure is clearly a network of straight lines in a plane, but we perceive it as a three-dimensional figure in space. If one fixes one's gaze so that the lower square appears to be the front face of the cube, then after less than thirty seconds one's perception involuntarily changes so that the sipper square becomes the front face. However one can intentionally override this and switch back to the original" perception - and back again if so desired.

The above by no means exhaust the reasons against what Popper calls the bucket theory of the mind, the idea that experience is just passively collected. Above all there is the mechanism of attention whereby of the mass of sensory material reaching the brain at any one time, only a fraction is admitted to consciousness. What is perceived depends upon attention, upon interest, and upon what has previously been perceived. To a degree we see what we are watching and hear what we are listening to. This is yet another of the same kind of illusion: it looks like direct experience, but it is really interpretation.

'There is no such thing as association or conditioned reflex', wrote Popper (O.K.67), and he later amplified the statement: `I do not at all question the correctness of the "conditioning" and "reinforcement", and "learning" experiments; but I give them and the learning process a different interpretation' (personal communication). The wealth of observation that has accumulated from learning experiments is not invalidated by the suspicion that conditioning and association are untenable hypotheses, but the observations will need reinterpretation in the light of a better theory. And I cannot help suspecting that some experimental results which have been presented as though they were universal phenomena will turn out to be singular events.

Eysenck made a revealing admission in his account of J. B. Watson's 'little Albert' experiment, commonly regarded as a classic in the application of conditioning theory to the treatment of the neuroses. By hitting an iron bar with a hammer whenever Albert reached out to touch a white rat, Watson gave him a pathological fear of white rats and other small furry animals. However, Eysenck says: `Watson was lucky in his choice of subject; others have banged away with hammers on metal bars in an attempt to condition infants, but not always with the same success.' Other accounts of this experiment have been less frank than Eysenck's (e.g. Salter and Wolpe), and have allowed it to be assumed that conditioning of this sort is as predictable as a chemical reaction. Eysenck explains the failure in terms of the great variation of inherited `conditionability'. A simpler, Popperian, explanation might be that what was repetition-for-Albert was not repetition-for-everybody.

Interestingly enough, Skinner in his interview with David Cohen makes the same kind of admission with regard to Pavlov. 'He was dealing with ... just about the only gland that would have worked. It's an amazing accident that he hit on it. It's very hard to find another gland that could be used ... You can't use tears. You probably could have used some other gastric secretions if you could get at them more easily. But I doubt that you could use urine or sweat. Salivation was it. As a matter of fact ... you might say that Pavlov was a specialist in conditioned salivation.'

The conditioning experiments are not questioned, nor is it denied here that the theory can be useful in practice, just as rules of thumb are useful - often more useful than exact calculations. What must be dismissed is the tendency to say `this is all there is to human behaviour - stimulus and response, positive and negative reinforcement'. It is the fanciful and naive generalisations of a philosophical nature, allegedly deduced from conditioning theory (itself perhaps a generalisation from the salivation of dogs), that must be firmly rejected; generalisations which pose as 'proof' that traditional values and ideas of truth and free will can no longer be taken seriously by those who consider themselves well informed and up to date. I am thinking of such works as B. F. Skinner's Beyond Freedom and Dignity, Nigel Calder's book and television series The Mind of Man, and an article in New Scientist entitled 'The shadow of the mind' by Professor John Taylor.

'Physiological' psychology, a new discipline started independently by Pavlov in Russia and Thorndike in the U.S.A. at the end of the nineteenth century, was a reaction against the earlier introspective psychology which was criticised as subjective and therefore unscientific. The raison d'etre of the new science was its objectivity. Its extreme proponents took the view that only what could be independently observed existed. It is ironical that they should have enthroned as their central concept this conditioning process, this unobservable and perhaps mythical process in the cerebral cortex.

What I hope I have demonstrated in these two chapters is that the current tendency to explain all human thought and behaviour in terms of (unsubstantiated) theories of unconscious psychology tends, in the first place, to distract from the central importance of rationality and reasonableness and conscious responsibility, which as I have already shown form the only known alternative to violence, as well as being our peculiarly human qualities. In the second place the cult of psychology distracts from the practical things that can be done to improve our society by way of improving its institutions and inventing new ones. We cannot change human psychology but we can change our institutions, little by little, and - to use the phrase already quoted - these can make an incalculable difference to human happiness.